1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device with use of an SOI (silicon on insulator) substrate. The present invention particularly relates to a bonding SOI technique, and also to a method of manufacturing a semiconductor device with the use of an SOI substrate obtained by attaching a single crystal or polycrystalline semiconductor film to a substrate with an insulating film interposed between the semiconductor film and the substrate.
2. Description of the Related Art
Demands for higher integration, higher operation speed, higher performance, and lower power consumption have been more stringent, and in response to such demands, a transistor using an SOI substrate has attracted attention as an effective means that can take the place of a bulk transistor. Higher operation speed and lower power consumption can be expected more in the transistor using the SOI substrate than in the bulk transistor because an insulating film is formed over a semiconductor film in the transistor using the SOI substrate, and accordingly parasitic capacitance can be reduced and generation of leakage current flowing through the substrate can be suppressed. In addition, since the semiconductor film used as an active layer can be formed thin, a short channel effect can be suppressed; thus, an element can be miniaturized and higher integration of a semiconductor integrated circuit can be realized accordingly.
As one method of manufacturing an SOI substrate, a method is given in which a semiconductor film is attached to a substrate with an insulating film interposed therebetween, such as UNIBOND (registered trademark) typified by Smart Cut (registered trademark), ELTRAN (epitaxial layer transfer), a dielectric separation method, or a PACE (plasma assisted chemical etching) method. The above-described attaching methods make it possible to form over an inexpensive glass substrate, a high-performance integrated circuit which uses a single crystal semiconductor film.
For example, Patent Document 1 (Japanese Published Patent Application No. 2004-087606) has disclosed a method of manufacturing an SOI substrate by attaching to a glass substrate, a semiconductor film separated from a bulk semiconductor substrate.